The present invention relates to an all-wheel-drive type vehicle for construction work.
As the driving mechanism for an all-wheel-drive type vehicle for construction work, it is conventional to adopt the so-called inscribed gearing construction for each of the respective reduction gearing means provided for every wheel close to same as the terminal gearing to receive power from the respective front or rear differential gearing. More specifically, an outwardly located annular gear is fixed to and rotates with the wheel, while a center gear is fixed to and rotates with the driving axle extending from the differential gearing as one of the output shafts thereof, and a plurality of intermediate gears are provided, on respective shafts journaled in fixed positions, for free rotation in meshing with both the annular gear and the center gear.
Such general adoption of the inscribed gearing construction is based perhaps on the common recognition of the compactness of the over-all mechanism, compatibility with the requirement of obtaining a wide steering angle range of the dirigible wheels, and the advantage of adopting as many unified parts as possible both in reducing the costs and in simplifying the design.
However, the inscribed gearing construction is of rather complicated structure and is therefore still expensive even if adopted as the common unified parts. Another drawback of the inscribed gearing construction resides in that the level of the driving axles is substantially the same as the center of the wheels, without possibility of freely raising same, thus leaving the risk of damaging the differential and axle housings, especially in the case of the non-dirigible wheels which are normally to support a heavier load than the dirigible wheels and are thus apt to sink down into the soil.